I have a MacBook Air and I'm using win to usb to run Windows 10 via a 64Gb USB stick.

I use it mainly for a few older games and it's running well however I have a couple of questions:

When I boot into Windows I've noticed the C drive is created from a VHD file contained on the USB stick. The file and the remaining space show as the D drive. Some things such as the DX9 files I need for older games install to the virtual C drive so space is very tight. Is it
possible to resize the virtual drive? Does running software from the VHD incur any noticeable performance decrease over running directly from the stick?

Secondly I've tried to update Windows 10 however after downloading the updates Windows states it can not install to a virtual hard drive. How can I fix this?